Standard activated carbons have been employed in the purification of contaminated glycol scrubbing solutions that are used in liquid-liquid extraction processes in the manufacture of petrochemicals. See for example, Technical Bulletin No. 23-62, copyright 1978, Calgon Corporation, Pittsburgh, Pa., which is herein incorporated by reference.
The use of standard activated carbons in a glycol scrubbing solution purification system causes an unacceptable depression of pH within the glycol stream when a new carbon supply is installed or when the exhausted carbon is changed. This pH drop is undesirable because isotherms indicate that carbon adsorptive capacity for colored impurities from a glycol scrubbing solution is best at high pH (.gtoreq.6).
It has been discovered that this pH drop is reduced when an activated carbon containing magnesite is employed.